The production of proteins for biopharmaceutical applications typically involves the use of cell cultures that are known to produce proteins exhibiting varying levels of heterogeneity. Such heterogeneity includes, but is not limited to, the presence of product-related species, such as charged species heterogeneity, consisting of acidic species and basic species. In monoclonal antibody (mAb) preparations, such acidic species heterogeneities can be detected by various methods, such as WCX-10 HPLC (a weak cation exchange chromatography) or IEF (isoelectric focusing). In certain embodiments, the acidic species identified using such techniques comprise a range of product-related substances such as antibody product fragments (e.g., Fc and Fab fragments), and/or post-translation modifications of the antibody product, such as, deamidated and/or glycoslyated antibodies. For example, in a sample of the human IgG antibody adalimumab, WCX-10 analysis measured the presence of acidic species that can be divided, based on residence time, into two groups: acidic region 1 (AR1) and acidic region 2 (AR2). Because of their similar chemical characteristics to the antibody molecules of interest, reduction of acidic species is a particular challenge in monoclonal antibody purification.
There remains a need in the art for high-efficiency methods of purifying proteins of interest, e.g., antibodies, away from product-related substances and process-related impurities at relatively low cost. Reduction of such substances and/or impurities is particularly advantageous in the context of commercially produced recombinant bio-therapeutics as such substances and/or impurities have the potential to impact numerous product characteristics, including, but not limited to, product stability, product safety and product efficacy.